1. Field of the Invention
The present invention relates to an improved method for the treatment of radioactive organic wastes wherein the wastes are decomposed by oxidation through the use of hydrogen peroxide.
2. State of the Art
At a nuclear power plant, condensed water, which is obtained through evaporation and concentration carried out at the time of treatment of waste water containing radioactive material, undergoes removal of salt and is reused. Because the granular or powdered ion exchange resins used in this process are contaminated with radioactive material, they should be treated to be made harmless. There is a similar problem concerning the organic filter aids which are used in the filtering of waste water.
The ultimate treatment of these radioactive organic wastes is solidification using cement, asphalt, or plastic. But, in order to isolate the wastes as safely as possible from the environment for a long period of time, and in order to decrease the volume as much as possible, it is desirable to proceed with the solidification process after the organic compounds in the radioactive wastes have been transformed into inorganic substances such as CO.sub.2 or H.sub.2 O through decomposition by oxidation.
The decomposition by oxidation of the organic solid wastes is broadly divided into dry methods and wet methods. Included in the latter wet method are the acid decomposition method, the Zimmermann Process, and the hydrogen peroxide method. The prior art relating to the hydrogen peroxide method includes a technique for oxidizing ion exchange resins in the presence of iron ions and/or chromium ions (Japanese Patent Disclosure Number 57-1446), a technique using anion exchange resins in the presence of (bi) chromate ions (Japanese Patent Disclosure Number 57-191599), and a method, proposed by the applicant, which oxidizes anion exchange resins, chelate resins, and filter sludge, all in the presence of iron ion and/or cation exchange resins (Japanese Patent Disclosure Number 58-72099).
In any of the known methods, evaporation of water from the system occurs vigorously because the reaction is carried out at a temperature raised to a certain point in order to promote decomposition by oxidation, and also due to heat generated by the reaction. The concentrated residual liquid is solidified, and the effluent, after being purified by desalting, is reused.
However, there are problems with the prior art. The effluent contains a large amount of organic matter which is considered an intermediate product (not yet a final oxidized substance such as CO.sub.2 or H.sub.2 O) of the oxidation reaction. This organic matter increases the burden on salt removal equipment, bringing about the need for a process to treat the remaining organic matter.